However, problems do occur. Say you go to just vsix.us and your IPv6 is not configured properly, returning your IPv4 address. You fix the problem, reload, and then... still IPv4?

Caching occurs at several levels: your browser, your local DNS resolver, your ISP's DNS server, etc. But fear not! Simply go to anything.nocache.vsix.us. This will return a site with both published IPv4 and IPv6 addresses, and with no DNS caching.

However, things still happen. Your browser could still cache one address over another. Your ISP may be caching DNS too aggressively. (That's polite speak for "they're breaking the rules".) And so on. In that case, simply choose another random subdomain. May I suggest squivionct.nocache.vsix.us?

About

This site was created by Ryan Finnie. There are already several "what is my IP(v6)" sites out there, but this site was created because:

The domain is short.

It has no numerals in the domain, making it easier to type in a mobile device. (Switching to the numeral mode on the iPhone wastes precious seconds!)

It has extra test functionality in the form of the nocache wildcard.

Other tidbits:

This server has native (not tunnelled) IPv6 connectivity, and vsix.us is served by DNS servers with full IPv6 DNS glue, allowing for end-to-end IPv6 DNS resolution. That means if you only have IPv6 connectivity, you'll still be able to reach this site, and if IPv4 were to go away tomorrow, this site would still function.